BCH210H1 Lecture Notes - Lecture 2: Acid Dissociation Constant, Aspartic Acid, Hydrophobicity Scales

• School: UTSG
• Department: Biochemistry
• Course: BCH210H1
• Professor: Reinhart Reithmeier

Document Summary

Zwitterions: neutral molecules, that have non-adjacent positive and negative charges: all amino acids are zwitterions (at neutral ph, positive amine group (-nh2), negative carboxyl group (-cooh) 20 amino acids: 10 come from the diet, joined through peptide bonds. Small, so used in tight protein packing & - helix. Commonly used in mutagenesis: to see effects of specific aa, convert into ala to see the changes. Indole ring: fluoresce (for detection of molecule, absorbs light at 295nm, fluoresces at 350nm, responds to environmental changes. In hydrophilic environment- fluorescence decreases: can monitor conformational changes, by monitoring the change in fluorescence (!!!) Nh group can hydrogen bond with water. D-isomer is made by other pathways in the body. In nature, mainly made up of l-isomers (through protein synthesis) B/c small, used in tight protein packing. 3 methyl side chain: very hydrophobic, buried inside proteins. 4 methyl side chain: with beta carbon, more hydrophobic than valine.